T-square



W. L. BOON.

v T sQUARE.

APPLICATION FILED JULY 19,1920.

LA; 1955544, Lamm June L3, 1922.

` L @gj 274413 L L Mg/Md Haan VJILE'RED L. BUON, OF NORTH l@ fi gli itl.iQ-ih Ll.

ATTLEBORQ, IIILSSLCHUSETTS.

' P-SQUARE.

Application filed July 19,

To all 107mm t may concern.'

Be it known that l, 'ii/Turnen L. Boon, a subject oi' the. King of GreatBritain, residing` at North Attleboro, in the county of Bristol andState ot Massachusetts, have invented certain new and useiiullimprovements in T-Squares, oi" which the following is specification.

This invention relates to improvements in T-squares used moreparticularly on drawing boards, and has for its object to provide asquare of this character with a gripping jaw slidably mounted on theblade thereot to cooperate with the working edge ot the edge ot the headof the square to automatically grip the board between them and so holdthe square in adjusted position on the board.

The nature and advantages of the invention will be better understoodwhen the 'following detail description is taken in connection with theaccompanying drawings, the invention residing in the combination andarrangement of parts as claimed.

ln the drawings forming part of this specification, like numerals olreference indicate similar parts in the several views and wherein Figure1 is a plan view ot my improved square showing the gripping jaw asbinding the square to a drawing board shown 1n dotted lines.

Figure 2 is an edge view of the square partly in section, shown asgripping a board which is illustrated in dotted lines.

Figure 3 is asection throuo'h the square showing the jaw with 'itsbinding screw en.- gaging the connector member.

llt is found in practice much easier to work upon a drafting board whichis set ou an incline, and, ordinarily, to operate i. T-square on such aboard it must'be connected thereto by means or' an elaborate arrangementot wires and pulleys so as to hold it square in adjusted position whenmoved up or down over the surface of a board, but such an arrangement isYtound quite expensive and is not practicable to be applied to allboards.

My improved attachment is adapted to be readily applied to any "l'squareand by its use a T -square oi the ordinary type may be applied to anyboard and caused to stay in any adjusted position on the boardregardless ot its inclination when moved up or down over its face.

Specification of Letters Llatent.

192D. Serial No. 397,289.

The following is a detail description of one means by which this resultmay be acconiplishe'L z* lV ith reference to the drawings, 10 designates the head of an ordinary T-square, the inner or working edge otwhich is adapted to engage and slide on one edge oithe drawing board 12.

To this head member is secured the ordinary blade 13 of the square, thelength of which should be slightly greater than the width of the boardto which the square is applied.

0n this blade l have slidably mounted a gripping member or jaw l-l whichtomprises an upper plate 15 and a lower plate 16 riveted togetherthrough the spacers 17 and these plates are separated sutliciently toprovide a space between them suliicient to receive the blade.

.On the upper plate 15, I have secured a looped-shaped member 18 throughwhich the connector wire, presently described, passes and through theupper wall of which l have threaded a binding' screw 19 to grip the wireand hold this jaw in adjusted position thereon. 'llo the lower plate 16ot this bar l have secured a binding finger 20 which extends downwardlytherefrom to engage the edge 22 of the drafting board, which is oppositethat engaged by the working edge 11 oi' the head.

Un the outer edge ot this head l have mounted a spring-tension lever 23which is secured at one end to the edge ot the head by means ot the clipQ-ele. This lever is preiterably constructed ot a strip ot resilientsheet metal having its operating end raised a suitable distance trom theedge ot the head, and to this lever is secured one end ol the connectorwire 21. which leads through the guide 25 and through the member 18 et'the aw, its opposite end being connected to the coiled spring 26 whichis considerably lighter in tension than the spring in the lever 23. Thislight spring 26 is preferably housed in the casing 27 secured near theouter end of the blade.

ln order to facilitate operating this T- square, i have attached a thumbclip 28 to its head portion so that in moving the square up and downover the tace ot the drafting board it is only necessary to engage theclip 28 with the thumb while the finger presses inwardly on the tensionlever 23 which pressure relieves the tension on the wire conll O nector2l permitting the lighter spring 26 to draw the clamping jaw fromgripping engagement with the edge 22 of the board; then the Tsquare maybe readily moved up or down over the surface of the board and whenpositioned the grip of the hand on the lever 23 is released, permittingthis lever to move outwardly and so overcome the tension lon spring 26causing the jaw to engage the edge 33 of the board, which cooperatingwith the working edge 11 of the nlsquare, grips the board between themand holds the square in adjusted position thereon.

In some instancesthe difference between the spring members 23 and 26 isso slight that the T-square may be easily moved in any adjusted workingposition without operating vthe lever rilhe device is extremely simpleand prac tical in construction and effective in its operation.

The foregoing description is directed solely towards the constructionillustrated, but l desire it to be understood that l reserve theprivilege of resorting to all the mechanical changes to which the deviceis susceptible, the invention being delined and limited only by theterms of the appended claims.

I claim:

l. A T-square for drawing boards comprising a blade with a cross-headconnected thereto at one end, a gripping jaw adjustably mounted on saidblade, a spring-tension lever on said head, a light spring at theopposite end of the blade, a connector extend ing from said lever tosaid light spring, and said jaw being adjustably connected to saidconnector, whereby said lever spring overcomes the tension of said lightspring to cause said jaw to cooperate with said head to grip the boardbetween them.

2. Tsquare for drawing boards comprising a blade with a cross-headconnected thereto, a grip jaw slidably mounted on the blade, a tensionmeans secured at the end portions of the blade, the tension means at thecrosshead end of the blade being stronger than the other, a flexibleconnector having its ends attached to said tension means at each end ofsaid blade, means whereby said jaw may be adjustably connected to saidconnector at any point along its length causing the jaw to cooperatewith the working edge of the cross-head to grip the board between them.

3. A. llsojuare for drawing boards comprising a blade having across-head connected thereto at one end, a gripping jaw having a slot'therein for slidably receiving said blade, a compressible means at thecross-head end of the blade, a tension spring secured at the other endof the blade, a flexible connector connecting said spring andcompressible means, said compressible means normally holding saidconnector taut, said jaw having a passage therein through which saidconnector extends, and a binding screw threaded in said jaw andextending in said passage for adjustably securing said jaw to saidconnector along its length.

4. A T-square for drawing boards ccmprising a blade provided with across-head at one end thereof, a grip jaw slidably mounted on the blade,a spring tension lever mounted on said cross-head and extendingsubstantially longitudinally thereof, and means connecting said grippingjaw and said lever.

5. A isquare for drawing boards comprising a blade provided with across-head at one end thereof, a grip jaw slidably' mounted on theblade, a spring tension lever mounted on said cross-head and extendingsubstantially longitudinally thereof, means connecting said gripping jawand said lever, and a linger-grip at the cross-head end of the bladearranged in such relation to said lever so as to facilitate theoperation of the lever for releasing tension on said jaw.

6. El 'iT-square for drawing boards comprising a blade provided with across-head at one end thereof, a grip jaw slidably mounted on the blade,a spring tension lover mounted on said cross-head and extendingsubstantially longitudinally thereof, a lighter spring secured to theother end of the blade, a connector extending between the said lever andlighter spring and attached thereto, a means for adjustably connectingsaid jaw to said connector along its length.

In testimony whereof l alix my signature.

WILFRED L. BOON.

